1. Field of the Invention
The present invention relates to a high frequency module including an inductor that is provided inside a multilayer body by a conductor pattern, and a capacitor that is connected to the inductor.
2. Description of the Related Art
Hitherto, various types of high frequency modules have been devised in which conductor patterns are provided in insulator layers constituting a multilayer body, to thereby form an inductor and a capacitor inside the multilayer body. For example, Japanese Unexamined Patent Application Publication No. 2008-271420 discloses a high frequency module in which an FET switch including a common terminal connected to an antenna and a plurality of switching terminals is mounted on a surface of the multilayer body, and a low pass filter connected to the FET switch is constituted by an inductor and a capacitor formed inside the multilayer body.
The interior of the multilayer body of the above-mentioned high frequency module of the related art generally has a structure illustrated in FIGS. 12 and 13. FIG. 12 illustrates an exemplary inner configuration of a multilayer body 100P constituting the related-art high frequency module, when looking at the multilayer body 100P from the lateral surface side thereof. FIG. 13 illustrates an exemplary configuration of inner conductors in the multilayer body 100P constituting the related-art high frequency module, when seeing through the multilayer body 100P from the top surface side thereof. It is to be noted that, while the high frequency module includes the multilayer body 100P and mount-type components, such as a switch element, which are mounted to the top surface of the multilayer body 100P, the mount-type components are not illustrated in FIGS. 12 and 13.
The multilayer body 100P is formed by stacking a plurality of insulator layers 101. In upper one of the insulator layers, layout conductors 200 are mainly formed to connect the mount-type components to circuit elements formed inside the multilayer body 100P. In a layer under the upper insulator layer where the layout conductors 200 are formed, an inner ground conductor pattern 300U is arranged to extend substantially over an entire surface of the layer.
Inductor conductor patterns 401P and 402P constituting respective inductors are provided on intermediate layers of the multilayer body 100P. The inductor conductor patterns 401P and 402P are each provided on a spiral shape with a spiral axis extending in a stacking direction. Thus, respective axial directions of the inductors formed by the inductor conductor patterns 401P and 402P extend in the stacking direction.
Capacitor conductor patterns 501P, 502P and 503P constituting capacitors are provided on layers under the intermediate layers of the multilayer body 100P where the inductor conductor patterns 401P and 402P are formed. The capacitor conductor patterns 501P, 502P and 503P are each a conductor in the form of a flat plate that is parallel to the corresponding layer and that has a predetermined area.
Just above a lowermost layer of the multilayer body 100P, an inner ground pattern 300D is arranged to extend substantially over an entire surface of the layer.
Meanwhile, in the related-art high frequency module described above, miniaturization is demanded, and the spacing between the inductor conductor patterns 401P, 402P and the capacitor conductor patterns 501P, 502P and 503P is inevitably narrowed with further size reduction.
For example, in the case of the structure where the inductor conductor patterns 401P and the capacitor conductor pattern 501P are arranged, as illustrated in FIGS. 12 and 13, in overlapped relation for size reduction when looking at the multilayer body 100P in a plan view (i.e., when looking at the multilayer body 100P in a direction perpendicular to the top surface thereof), a distance G0 (taken along the stacking direction) between the inductor conductor patterns 401P and the capacitor conductor pattern 501P is shortened.
Thus, because the axial direction of the inductor formed by the inductor conductor patterns 401P is parallel to the stacking direction, the distance from the inductor formed by the inductor conductor patterns 401P to the flat-plate conductor constituting the capacitor conductor pattern 401P is shortened.
In the above-described structure, a magnetic field generated from the inductor is blocked off by the capacitor conductor pattern. As a result, a Q value of the inductor deteriorates, and circuit characteristics of a filter, including the inductor, and of the high frequency module degrade.